The foremost of these is the K-5IIs, which, hugely, looses the dreaded Anti-aliasing filter. This is the first APS-C sized camera to take that brave step, following in the D800E’s lead.
This is potentially a big deal
, but I could barely get anyone to even explain it to me. Ugh.

Just back from Köln (visited Photokina yesterday).

Most people on the Pentax stand were OK in terms of knowledge (though some knew more than others), taken into account that most were interims, which is customary on trade shows like these, esp on the bigger stands. Actually, among the big ones Pentax stand staff was above average. Sigma for instance was a complete disaster. But getting information on the technical details wasn't obvious indeed.

For some questions the person asked had to find someone else for the answer, but the were helpful in trying to do so, even if they didn't always succeed (many many people on the stand).

Concerning your point, i.e. the difference between the K-5II and the K-5IIs, my question on the topic went partly unanswered as well, in as much that the (2nd) person I talked to couldn't
show
me the difference let alone confirm whether it was substantial or not, though he could more or less explain the concept behind the removal of the AA-filter. He told me he couldn't show anything since they hadn't received information on the subject (though in the interview conducted by pentaxforums the engineer did show a comparison) because no final firmware was available. He
did
inform me that with some of the other staff he had tried to cause Moiré with the K-5IIs using a target with repeating patterns they had looked up esp for the test and that they hadn't succeeded getting a single shot with Moiré, though the had noticed a clear advantage in sharpness. But nothing to show...

It was a matter of being able to talk to the right person... which was not always as easy because of the crowds.

Of course, on smaller stands things were different. I had a very nice chat with the people of LensBaby for instance, and Gary Fong was personally explaining his products at his small stand. It was a very interesting edition BTW, mostly because I skipped C & N to have more time to visit the much more interesting smaller stands. I'll write up a longer report on all I learned at Photokina when I have the time...